1. Field of the Invention
This invention relates to a device for measuring a dimensional change of materials and more specifically relates to a device for measuring dimensional change of concrete, polymeric materials and the like.
2. Description of the Prior Art
It is well known that polymeric materials and concrete undergo a dimensional change during polymerization or setting and often with the evolution of a moderate to large quantity of heat of polymerization. Most frequently, the dimensional change which occurs is a shrinkage of the these materials in dimensions. This dimensional change can cause dimensional instability problems of the resultant polymerized or cured polymer in the form of cracks. It would be useful to be able to accurately measure the dimensional change which occurs in a material and more particularly in a material undergoing polymerization or "setting" as a function of time. With this data, polymerization studies could be made which minimize the effects of dimensional change upon the dimensional instability of the final product. Shrinkage results because the heat of polymerization causes the evaporation of volatile monomers or components or the resultant polymerized material has a greater density than the precursor polymerizing mass.
At present, the method available for measuring dimensional changes published by the American Society for Testing Materials (ASTM) relate to Portland Cement mortar (ASTM C 157/75 and C 490/77). These ASTM methods do not provide for the accurate measurement of the dimensional change of polymeric materials.